Aluminum alloys



Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE ALUMINUM ALLOYS NoDrawing. Original application September 21,

1932, Serial No. 634,155. Divided and this application November 645,115

2 Claims.

This invention relates. to aluminum base alloys containing magnesium.The invention has for its object the improvement of alloys of this classby the addition thereto of about 0.05

to 2.0 per cent by weight of calcium. The invention is particularlyconcerned with the specific alloys hereinafter described.

The claims of this application cover certain matter divided from mycopending application Serial No. 634,155 which is, in part, acontinuation of my copending application Serial No. 595,231. Inventionsdisclosed but not claimed herein are claimed in my copendingapplications Serial Nos. 595,231, filed February 25,' 1932, 645,108, to645,114 inclusive, and 645,116 to 645,125 inclusive, all filed November30, 1932.

Considerable difficulty has heretofore been encountered in attempts tocommercially produce castings of aluminum base all'oys containingsubstantial amounts of magnesium. This diiiiculty is encountered both inthe making of sand castings and permanent mold or chill-mold castings,although the nature of the difiiculty differs somewhat in each case. Inthe case of cand castings there occurs a reaction between the moltenaluminum base alloy containing magnesium and the ordinary sand-moldmaterials, or vapors generated therefrom. There is also a reaction withthe atmosphere. In addition, the magnesium-containing aluminum basealloy does not flow freely through narrow mold sections at ordinarypouring temperatures and, if the pouring temperature be raised, thesolidified alloy is unsound. If the aluminum base alloy containingmagnesium be cast in a chill-mold the reaction effect is minimized tosome extent, but the troubles arising from cold-shuts and mis-runs areaccentuated because of the more rapid chilling of the molten metal. Theconsiderations apply to the aluminum base alloys specifically disclosedherein and particularly to such alloys.

I have discovered that when calcium is added to aluminum base alloys ofthe type and composition herein described, these difliculties are, to

a considerable extent, eliminated. The calcium should be present inamounts ranging from 0.05 per cent to 2.0 per cent by weight subject tospecific considerations as hereinafter disclosed.

In the melting of aluminum alloys of the compositions herein described,a viscous scum 30, 1932. Serial No.

a resistance to the free passage of the metal through the apertures.Regardless of the cause of this low. fluidity, I have discovered thatthe addition to the alloy of relatively small amounts of calcium, in thepreferred range between 0.05 to 0.5 per cent, improves the castingcharacteristics to a very considerable extent and simultaneously effectsa reduction of the scum or dross collecting at or near the surface. Inthe casting of articles in sand molds, I prefer to add calcium inamounts less than about 0.5 per cent except in instances where somereduction of tensile strength or other mechanical or tensile property isimmaterial. In amounts of more than 0.5 per cent the calcium additionproduces the advantages enumerated herein but has a tendency to lowersome of the physical properties of the alloys. This effect is notharmful when calcium is present in amounts of about 0.5 per cent orless, but when high strength is not a desideratum the calcium may beused in amounts up to about 2.0 per cent. In intricate permanent moldcastings, where casting troubles are very serious if no calcium beadded, the improved physical properties obtained coincident with theproduction of good castings more than offset the diminution inproperties which might otherwise result from the use of the calcium.

I have also discovered that when calcium is added to aluminum basealloys containing magnesium, the amount of gas evolved duringsolidification of the alloys is considerably reduced. When from about0.05 per cent to 2.0 per cent by weight of calcium is added to thealloys, the amount of gas evolved becomes less marked with increasingcalcium content and the reduction of gas evolution may be so marked thatthe molten metals cools to the solidification temperature with asmooth-like surface. I prefer to restrict the amount of calcium added to2.0 per cent or less since above this amount the physical properties ofthe alloys may be too seriously affected. Ifthe best physical propertiesaredesired with an improved, although not complete, degree of gasprevention, I keep the calcium content of the alloys between 0.05 percent and about 0.5 per cent.

In the application of the principles of my invention I have determinedthat certain aluminum base alloys containing magnesium are particularlybenefited thereby. For example, a very useful aluminum base alloy is onecontaining about 2.0 to 9.0 per cent of magnesium and 0.05' per cent to2.0 per cent of calcium, as is also aluminum base alloy containing about2.0 to

15.0 per cent of magnesium, 0.1 to 3.5 per cent of cobalt, and 0.05 to2.0 per cent of calcium to which other elements such as copper,antimony, bismuth, nickel, manganese, and other well known alloyingelements may be added to produce particular properties therein.

Likewise is the' addition of 0.05 to 2.0 per cent of calcium beneficialto those aluminum base alloys which contain about 2.0 to 15.0 per centof magnesium and 0.05 to 0.4 per cent of at least one of the class ofmetals here defined as antimony and bismuth, such alloys being veryuseful where use at high temperatures is contemplated. Calcium maylikewise be added to improve such alloys when they contain, in

addition to magnesium and antimony and/or bismuth, one or more of suchalloying elements vas cobalt, copper, nickel, manganese, zinc, etc. vwhich may be added to modify or produce a specific property in thealloy.

The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of aluminum base alloys which contain as majoralloying elements about 2.0 to 10.0 per cent of magnesium and about 0.2to 5.0 per cent of nickel. For instance, an aluminum base alloycontaining 3.0 to 7.5 per cent of magnesium and 0.2 to 2.0 per cent ofnickel is improved by the addition of 0.05 to 2.0 per cent of calcium asis, likewise, this same alloy when it also contains about 0.05 to 0.4per cent of one or more of the class of elements composed of antimonyand bismuth. Another excellent aluminum base alloy prepared inaccordance with the principles of my invention is one containing 3.0 to8.0 per cent of magnesium, 0.5 to 4.0 per cent of nickel, 0.5 to 4.0 percent of manganese, and 0.05 to 2.0 per cent 01 calcium, which alloy mayalso be improved, particularly for application at high temperatures, bythe addition of 0.05 to 0.4 per cent of at least one of the class ofelements composed of antimony and bismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium, andaluminum base alloys containing magnesium, nickel, and copper, as wellas those alloys containing magnesium, nickel, and cobalt. Examples maybe given of aluminum base alloys containing 2.0 to 10.0 per cent ofmagnesium, 0.2 to 5.0 per cent of nickel, 0.5 to 3.5 per cent ofchromium, and 0.05 to 2.0 per cent of calcium. An aluminum base alloycontaining 3.0 to 8.0 per cent of magnesium, 0.5 to 3.5 per cent ofnickel,

0.5 to 3.5 percent ofchromium, and 0.05 to 2.0 per cent of calcium hasexcellent casting properties and the high temperature properties of thisalloy can be favorably affected by the addition of 0.05 to 0.4 per centof at least one of a class of elements composed of bismuth and antimony.

Examples may be given of aluminum base alloy containing 2.0 to 10.0 percent of magnesium, 0.2

to 5.0 per cent of nickel, 1.0 to 6.0 per cent of copper, and 0.05 to2.0 per cent of calcium. An excellent alloy of this type is onecontaining 3.0 to 8.0 per cent of magnesium, 0.5 to 5.0 per cent ofnickel, 1.0 to 6.0 per cent of copper, and 0.05 to 2.0 per cent-ofcalcium with or without 0.05 to 0.4 per cent of at least one of theclass of elements composed of antimony and bismuth and with or withoutthe further addition of 0.5 to 3.5 per cent of at least oneof a class ofelements composed of cobalt and chromium, and with or without thefurther addition of 0.1 to 1.0 per cent of at least one of a class ofelements composed of tungsten, vanadium, molybdenum. titanium, andzirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent of calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class of elementscomposed of antimony and bismuth, is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel,

. 0.1 to 3.0 per cent cobalt, and 0.05 to 2.0 per cent calcium.

Among other magnesium-containing aluminum base alloys which I have foundto be particularly benefited by the presence of calcium are numbered thealuminum base alloys containing 3.0 to 8.0 per cent of magnesium, 1.0 to6.0 per cent of copper, 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0per cent of calcium, with or without the addition of 0.05 to 0.4 percent of at least one of a class of metals composed of antimony andbismuth and with or without the addition of other alloying elements. Thealloysherein described may be produced by the usual methods of alloyingmetals. The calcium is' preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The aluminum used in preparing the alloys may be pure or itmay contain the impurities found in commercial grades of this metal.Ordinarily a good commercial grade of virgin aluminum will giveexcellent results and is preferable.

Having thus explained and described my invention, I claim: 125

1. A metallic alloy consisting of 2.0 to 10.0 per cent by weight ofmagnesium, 0.2 to 5.0 per cent by weight of nickel, 1.0 to 6.0 per centby weight of copper, and 0.05 to 2.0 per cent by weight of calcium, thebalance being aluminum. 130

2. A metallic alloy consisting of 3.0 to 8.0 per cent by weight ofmagnesium, 0.5 to 5.0 per cent by weight of nickel, 1.0 to 6.0 per centby weight of copper and 0.05 to 2.0 per cent by weight of calcium, thebalance being aluminum. 1 5

ROBERT T. WOOD.

- (set n)- CERTIFICATE. OF CORRECTION.

humus. 1,932,861. October 31, 193.3.

ROBERT T; WOOD.

It is hereby certified that error appears in the printed specificationof the above numbered p atent requiring correction as follows: Page 1,line 94, for "smooth-iike" read smooth mirror-like; 'andthat the saidLetters Patent should he read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 5th day of becelhber A. D. .1933.

/ F. M. Hopkins Acting Conniasioner of Patente.

